الفهرس 
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Abstract
The present study was conducted at plant protection research institute in Zagazig. Th aim of this work was directed mainly to study the possibility of resistance development to pyriproxyfen by the most common insect of legumes to Pyriproxyfen, comparing with the development of resistance to one of the traditional insectisides which were extensively used for the control of stored product insects in the life history of the selected strain was also studied. The investigation was extended also to evaluate the efficiency of some IGR as protectants against the Cowpea beetle, Callosobruchus chinensis, field experiments.
The result of these experiments could be summarized as follows:
Part I: Laboratory Studies:
A- Resistance:
1. Development of resistance in the Cowpea beetle to Malathion
compound:
1.1. The selected strain:
The exposure of the Cowpea beetle adults every generation up to F20 progeny to selection pressure of Malathion failed to induce a high level of resistance strain,. Development of resistance was very slow and gradual recording 1.45, 3.08 , 7.57 and 11.30 fold only as a resistance factor in F5, F10, F15 and F20 progenies, respectively at the LC50 level.
1.2. The unselected (Laboratory) strain:
The susceptibility of the unselected laboratory strain (which reared in the laboratory away of any insecticidal treatment) to Malathion was increased from one tested generation to another at levels (LC50 as the period of rearing was prolonged . The slop of the regression lines increased relatively in the last three tested generations and they are approximately parallel.
2. Development of resistance to Admiral compound: 2.1. The selected strain:
The strain of the Cowpea beetle reared under the selection pressure of one compound of pyriproxyfen develop
resistance to it after 20 successive generations of selection at the concentration that kill 50% -60% of eggs .However, the
insects had been developed a high level of resistance at level ( LC50) recording 141.75 fold in F20.
2.2. The unselected (Laboratory) strain:
The susceptibility of the laboratory strain (reared
continuously) without any exposure to insecticides) to
pyriproxyfen was increased during the period of rearing. The LC50 decreased gradually from 1 .00 in parents generation to
0.54 , 0.48 ,0.13 and 0.16 in F5 , F10 ,F15 and F20 progenies, respectively.
Tolerance ratio decreased gradually at level of (LC50) recording (0.16 fold in the tested generation (F20 ).
3- Some biological changes in the life history of
Callosobrochus chinensis accompanied to the
selection pressure of Malathion and
Admiral compounds .
Some biological aspects i.e. number of eggs / female, hatchability
percentage, larval pentration, complete developmental
period,
emergence percentage, and sex ratio of Callosobrochus chinensis in Malathion and pyriproxyfen selected and unselected strains were studied during parents generation, F5,
F10, F15 and F20 progenies of the selection period. The results obtained can be summarized as follows:
a- Number of laid eggs per female:
Result show that Malathion and pyriproxyfen compounds of selected strains was affected significantly by the tested insecticides
and differed also from generation to another during selection pressure. The highest mean number of eggs was 56.25 eggs / female recorded for parent generations, then the eggs production
decreased gradually to 50.33, 43.25, 44.33, 38.50 and
32.00eggs/female in F5, F10, F15 and F20, respectively for
Malathion and pyriproxyfen. The mean numbers of deposited eggs per female of Malathion 42.35 and pyriproxyfen 34.43 eggs/female as comparing with 53.60 eggs/female for control. Production of eggs was markedly reduced by pyriproxyfen selection followed in ascending order by Malathion and control strains.
b-Hatchability percentages of laid eggs by survivors :
Different generations and the used insecticides affected significantly the hatchability percentage of deposited eggs by females. The highest percentage of hatchability was 94.09% noticed for laid eggs by parent and the least hatchability percentage of eggs 69.72% was recorded for F20. On the other hand, the least average of hatchability 63.44 % was recorded for eggs treated using pyriproxyfen compound compared with 88.18% for eggs treated using Malathion. The control had an average hatchability of 95.25%.
c-Penetration percentage:
The larval penetration percentage was affected significantly by the tested insecticides, the highest penetration percentage of larval 89.97% was observed for parents generation. On the other hand the lowest penetration percentage of 65.68% was recorded for F20 progeny. The selection pressure with pyriproxyfen was effective in reducing the larval penetration percentage than the Malathion treatment.
d- Complete developmental period:
Generation and insecticidal selection had highly
significant effect on the complete developmental period ( from egg deposition till adult emergence). The longest period of
146 4’ Summary
development 24.83 day was recorded at F20, this period decreased to 23.95 , 23.39 , 22.15 and 21.81 days for the insects of F15, parents F10 and F5 , parent, respectively .
On the other hand, the insecticidal selection with Malathion and pyriproxyfen Prolongated the complete developmental period of the selected insects.
Results Demostrated that treatment of Callosobrochus chinensis of
pyriproxyfen had a great potential on some biological aspects.
e-Percentage of adult emergence:
The percentage of adult emergence decreasing from laid eggs by females of the selected strains and it was affected significantly by the tested insecticides and generations. The
least percentage of adult emergence 63.61% and
63.33% were recorded at F15 and F20 progenies
respectively. Also, results revealed that pyriproxyfen
compound recorded a highly reduction in the percentage of adult emergence from the begining of selection (parents generation) till F20. But, Malathion began its effect on adult emergence from F10 and continued until F20.
f-Sex ratio as percentage of males:
Sex ratio of adults emerged from deposited eggs by females survivors of the selected strains was affected significantly by the tested insecticides and generations, in Malathion, females out numbered significantly that of males by 10.98 %, but in Pyriproxyfen males out numbered significantly that of females by 1 5.25% . Compared control strains, the males exceeded compared with females by 1.87% only .
4- Effect of three developmental inseticides,
Fenoxycarp, Hydroprene and Karapp compounds on the Southern Cowpea weevil, Callosobrochus chinensis (L.) eggs.
Present results proved that buprofenzin, fenoxycarp, hydroprene on compounds can be arranged in descending order
according to their potency against one day - old eggs of Callosobrochus chinensis (L.), at the LC50 levels as follows Juvenile hormone mimics, Altozar, Fenoxycarp and Buprofezen which caused median effective at LC50 values 1.05, 2.73, 15.4 and it was recorded at one day old eggs 5.63, 11.98, 2817.00 for three days, respectively.
Generally it could be concluded that Juvenile hormone compounds may be most useful for the protection of grain when applied to uninfested grain or when the grain containing low numbers of insects rather than infestation controls.
They could prevent building of infestations and this could be
elucidated too.
a-The possibility of Juvenile hormone compounds inducing caused some of physiological abnormalities to insects.
b-The females treated with Juvenile Hormone was (disturbing sex ratio in favorable of males) could increase the apportunity for obtaining infestation free seeds.
There was negative correlation between percentage hatchability (suscepitability) and age of eggs .
Part II- Field experiments:
The field experiments were carried out during the two successive Cowpea seasons of 2001 and 2002 at Zagazig region, Sharkia Governorate to study the effect of the sowing dates and varieties of Cowpea different, intercropping patterns of Cowpea and Maize and some pesticides compounds on Callosobruchus chinensis in Cowpea fields.
The following experiments were carried out to clarifg the effect of this different variables.
1- Effect of sowing dates on the infesttion of Cowpea
seeds with Cowpea seeds with, Callosobruchus chinensis at Zagazig region during 2001 and 2002 seasons.
The present results clearly show that sowing date of Cowpea plants had an highly significant effect on the infestation
of dry seeds of Cowpea with Callosobruchus chinensis in the field,during 2001 and 2002 season.
The highest mean percentages of seeds infestation (13.33, 15.00%) were occurred in seeds of Cowpea plant sown at the 1’ of june in the first and second seasons respectively .While, the lowest level of infestation (6.00 and 7.33%) were recorded with the first sowing date (at the 1st of April) in both seasons, respectively. On the other hand, Cowpea plants sown at the 1St of May showed that the median mean of infestation percentages of seeds ( 8.33 and 8.00%) were recorded in both seasons, respectively.
2- Effect of intercropping patterns of Cowpea and Maize on the infestation of Cowpea seeds beetle, Callosobruchus chinensis :
The differences between mean percentages of dry seeds infestation of Cowpea plants grown in different tested intercropping patterens were highly significant in both seasons. The Cowpea plants grown in pure stand were less infested with the Callosobruchus chinensis as compared with Cowpea plants grown in different inttercroping pattern of Cowpea and maize. The highest mean percentages of seeds infestation (10.33 and 9.33%) occured with seeds of Cowpea plants grown on the planting pattern, one ridge of Cowpea in alternation with one ridge of maize in first and second seasons, respectively. While, the median mean percentages of seeds infestation (5.0, 4.0 and 9.33, 8.0%) were occured with seeds Cowpea plants grown on the planting patterns slice of Cowpea in alternation with slice of Maize and one hill of Cowpea in alternation with one hill of maize in the first and second seasons, respectively.
2- Effect of varieties of Cowpea on the infesttion of Cowpea seeds with, Callosobruchus chinensis :
The results obtained showed highly significant differences between the tested Cowpea varieties in both growing seasons. The lowest mean percentages of infested seeds (3.33 and 5.33 %)
occurred with Dokki 335 variety during first and second seasons, respectively. While, the highest corresponding ones (21.33 and 25.0 %) were obtained with Fitrait variety in both seasons, respectively. On the other hand, Blacke eye and Cream7 varieties showed the median mean infestation percentage of (6.66 and 8.66%) in both seasons, respectively.
4- Evaluation of some compounds against Callosobruchus chinensis
in Cowpea fields :
The result obtained showed that:
Generally, Consult, Cascade, Dursban, Lannat and Atabron showed highly significant effect against Callosobruchus chinensis comparing with Bioclean, Xentari and Diple 2X. The highest mean of infestation percentages of seeds were (16.33 and 17%) recorded with Dipel 2x. The lowest corresponding ones were (3 and 3.66%) recorded with Atabron and Cascade comparing with 14.66 and 14% in untreated plots in both seasons, respectively. On the other hand, Bioclean and Diple 2X caused relative increase in the mean numbers of individuals (larvae, pupae and adults) per 100 seeds comparing with the control. Also, Atabron was the most efficient compounds against Callosobruchus chinensis in Cowpea fields followed by Cascade, Dursban, Consult, Lannet, Xentari, Bioclean and Diple 2X in the first season. While, in second season, Cascade was the most efficient compound against Callosobruchus chinensis followed by Atabron, Consult, Dursban, Lannat, Xentari, Bioclean and Diple 2X, respectively.
VI. CONCLUSION
Result show that Malathion and pyriproxyfen compounds of selected strains was affected significantly by the tested insecticides and differed also from generation to another during selection pressure and it could be concluded that Juvenile hormone compounds may be most useful for the protection of Cowpea grain when applied to uninfested grain or when the grain containing low numbers of insects rather than infestation controls. Also, results show that Malathion compound is more active than pyriproxyfen compound in cowpea beetle control. Cowpea plants sown at the 1st of April showed the lowest level of infestation percentages of seeds comparing with the other sowing dates in both seasons.
The Cowpea plants grown in pure stand were less infested with the Callosobruchus chinensis as compared with Cowpea plants grown in different inttercroping pattern of Cowpea and maize plants.
Also, results proved that the lowest mean percentages , of infested seeds occurred with Dokki 335 variety during first and second seasons, respectively. Our results proved that Atabron and Cascade compound was the most efficient against Callosobruchus chinensis in Cowpea fields in the first and second seasons compared with the other tested compounds.